1. Field of the Invention
This invention relates to hot water heaters and in particular to means for preventing blockage of flow through an inlet duct by lime formation at an upper level of water therein.
2. Description of the Prior Art
In Pat. No. Re. 21,393, of Joseph S. Losee, an electric water heater is shown wherein a basin is mounted above a heating tank with a delivery tube extending downwardly from the basin into the heating tank. The outlet from the heating tank is defined by a siphon which has an inlet opening into the upper portion of the tank. A heating element is provided in the lower portion of the tank for maintaining the water in the tank at a preselected high temperature. As shown in the patent, the water level during the water heating operation may be within a portion of the transfer duct below the basin.
It has been found that continual heating of water in such a water heater causes lime to form at the upper level of the water and, thus, lime may form across the transfer duct from the basin to the tank. Where such lime formation is permitted to accumulate over a substantial period of time, the lime blocks the transfer duct preventing proper operation of the water heater.
Such hot water heaters may be utilized in brewing apparatuses, such as for brewing coffee and the like. One excellent example of such a brewing apparatus is shown in U.S. Pat. No. 3,366,034, of Harvey R. Karlen et al, owned by the assignee hereof. Such brewing apparatuses may be installed in offices and the like and it is important to prevent overflowing of the basin as might result from the blockage of the transfer duct from the basin to the tank when cold water is being poured into the basin to displace a corresponding quantity of hot water previously heated in the tank outwardly through the siphon discharge duct to the brewing cartridge.